Backing up your bookmarks is a smart move -- in the event that you need to reinstall Firefox or switch to another browser, this process ensures that you won't lose the links to your favorite websites. Firefox makes it easy to export your bookmarks in several formats that are compatible with other popular browsers.
Click the bookmarks icon and select "Show All Bookmarks" to open the Bookmarks Library window.
Click "Import and Backup."
Select "Backup..." to export your bookmarks as a JSON file, or "Export Bookmarks to HTML" to save them as an HTML file. Select the folder to which you want to export your bookmarks and click "Save."